Asphalt or composite shingles are one of the most commonly used roofing products. Asphalt shingles generally include a base material made from organic felt or a fiberglass mat. The base material serves as a matrix to support an asphalt coating and gives the shingle strength. The asphalt coating is formulated for the particular service application. The asphalt coating has a long-term ability to resist weathering and provides stability under extreme temperature conditions. An outer layer of granules is applied to the asphalt coating to form an outer surface, which shields the asphalt coating from direct sunlight. The granules also offer resistance to fire. When manufacturing colored shingles, colored granules may be applied to the asphalt coating.
Although asphalt shingles offer significant advantages over wood shingles with respect to cost, service life, and fire-resistance, wood shingles are often preferred because of the pleasing aesthetic appearance of the wood shingle roof. An important aesthetic advantage of the wood shingle as compared to an asphalt shingle is attributed to the thickness of the wood shingle. The thickness of wood shingles produces a finished roof having a layered look with depth.
Various asphalt shingles attempt to provide an appearance of thickness comparable to that of wood shingles. Examples of such asphalt shingles are shown in U.S. Pat. No. 5,666,776, issued to Casimir Paul Weaver et al., U.S. Pat. Des. No. 379,672, issued to Glenn D. Lamb et al., and U.S. Pat. Des. No. 340,294 and U.S. Pat. Des. No. 375,563, both issued to Marcia G. Hannah et al. The Weaver et al. patent shows a laminated asphalt roofing shingle having color gradations from light to dark. The color gradations create the illusion of depth or thickness. The Lamb et al. patent shows a double-shadow shingle design comprising six generally rectangular areas of different shading with alternate shaded areas having a wide darker area or shadow line at the top and a narrow shadow line at the bottom. The Hannah et al. patents show a staggered shadow line. Some of the shadow lines are heavily shaded and some of the shadow lines are lightly shaded.